Effect of osmopriming treatments with mannitol on cottonseed germination performance under suboptimal conditions

Abstract

Summary The effect of osmopriming on germination performance of cottonseeds was investigated under suboptimal thermal conditions (12 to 24°C). Seeds were primed in mannitol solutions at three water potentials (-0.5, -1.0 and -1.5 MPa) for 6, 12 or 18 hours at four incubation temperatures (16, 19, 22 and 25°C) in darkness. The treated seeds and non-primed controls were then subjected to germination tests at 12, 15, 18, 21 and 24°C. Germination performance was evaluated by final germination percentage, time to reach 10, 50 and 90% germination, germination uniformity, and thermal time requirement. Osmotic potentials of -0.5 MPa and, to a lesser extent -1.0 MPa, tended to increase germination rate and uniformity in comparison with non-primed seeds. In addition, osmopriming resulted in a substantial lowering of the thermal time requirements for seed germination. In most cases, seed performance based on all the parameters considered was better for priming durations of 6 or 12 hours than for 18 hours. A trend for higher germination uniformity was apparent when seeds were primed at 19 and 22°C.